But even by those standards, their latest project is a bit peculiar: scoring an opera based on Charles Darwin's bookOn the Origin of the Species.

A studio version of the opera, called Tomorrow, In A Year, releases online Feb. 2, and on CD March 9 -- but you can hear all 16 tracks right now at the Knife's website -- and via this player:

Now, people, this is far from the catchy electro pop of "Heartbeats." Over two CDs, Tomorrow, In A Year jumps from wandering and skittering computer blips ("Variation of Birds") to tribal drums, drones, and operatic singing ("Tomorrow in a Year"). Some of the album's sounds were even recorded by Olof in the Amazon, where he traveled to find inspiration for the album.

Tomorrow, In A Year premiered last September in Copenhagen, and opens in Stockholm this weekend.

Oh, and in related news, Dreijer Andersson recently accepted another Grammis, this time for her side-project Fever Ray. Yeah... she spoofed Lady Gaga's red headdress from the VMAs -- then gave the weirdest damn acceptance speech while her face melted off. No joke. Watch below.